PTC fuel heater for heating alcohol fuel

Abstract

A fuel heater for vaporization of an alcohol fuel from a fuel line to an internal combustion engine for delivering vaporous fuel to a carburetor. The fuel heater includes a stack of generally planar foraminous PTC heaters that are arranged in a container having an insulated interior defining a fuel flow path having an inlet and an outlet and are separated from each other by generally flat ring-like conductive spacers with electrically conductive ears having conductor receiving holes therein. Alternate conductive spacers are disposed in two channels in a housing and connected to opposite sides of a power supply whereby said PTC heaters can raise the temperature of the incoming fuel and vaporize it. Alternative ears of the electrically conductive spacers are radially offset from each other whereby one row of ears is disposed in one channel and another row is disposed in the other channel.

As our invention we claim: 
     
       1. A fuel heater comprising: a container having an electrically insulated interior defining a fuel flow path and further having an inlet and an outlet, being connected to the opposite ends of said flow path for the passage of fuel therethrough; and   a stack of generally planar foraminous PTC heaters disposed in said container in the flow path between the inlet and the outlet and arranged transversely of the flow direction of the flow of fuel; and   an array of flat ring-like conductive elements, each having an electrical contact projecting from an edge thereof, the contact means of said array of elements being arranged in two rows, the electrical contact means in one row being arranged so as to be radially offset from the electrical contact means of the other row, each conductive element of each row being disposed between alternate PTC heaters in said stack, each of said conductive elements engaging substantially only the perimeter of the PTC heaters to leave the foraminous central portion thereof unobstructed to allow flow of fuel through said stack of PTC heaters from said inlet to said outlet; and   a pair of radially offset channels disposed on the interior of said container; and   electrical contact means of one row being disposed in one of said channels and electrical contact means of the other row being disposed in the other of said channels; and   means connecting the outsides of the opposite end-most PTC heaters in the stack to the opposite sides of a power supply and means connecting the electrical contact means of said one row and the electrical contact means of said other row to opposite sides of the same power supply.   
     
     
       2. The fuel heater according to claim 1 wherein the electrical contact means each has an aperture disposed therein and said means for connecting said electrical contact means of each row comprises a post disposed in the apertures of each row of electrical contact means and in electrical contact therewith, said posts being connected to said opposite sides of said power supply. 
     
     
       3. The fuel heater according to claim 1 or 2 wherein said means to connect the opposite end-most PTC heater are also planar ring-like conductive elements, each having electrical contact means projecting from an edge thereof. 
     
     
       4. The fuel heater according to claim 1 further including a spring means engaging the outside of an end-most conductive element, whereby to urge the elements and the stack of PTC heaters against each other and to insure electrical contact. 
     
     
       5. The fuel heater according to claim 4, wherein one of said inlets and said outlet for said fuel flow path of said heater is in a cover closing an end of the fuel flow path in said container, and said spring means is conically shaped, and at least a portion thereof engaging said cover and the edges of the cone engaging the outer perimeter of an end-most conductive element, whereby to hold the PTC heater assembly in place in the container.